The yearly costs of treating dental caries in children is enormous. In contrast to the time period prior to the 1960's, caries activity is now found primarily in a specific segment of this population. Obstacles in understanding this disease process making progress toward its eradication are (1) the poor understanding of the relative contribution of certain psycho-social and biological factors in the caries process and (2) the lack of a method to predict with high sensitivity and specificity individuals who are at high risk for caries. Previous caries prediction studies using single biological variables, evaluating caries activity as mean "dmf", and using coefficient of determination to measure the strength of association, have shown little success in correlating caries incidence to specific variables, or assessing caries risk in specific populations. Recent research by ourselves and others have shown improved results by using a combination of discriminators, by examining variables as "positive" or "negative", and by limiting the focus to well defined populations (i.e., children under age 6). The major objectives of this proposal are to (1) identify the factors associated with high caries risk in 500 low income children over a 3 year period, (2) develop a model that can reliably predict individuals at high/low risk to develop caries. Predictor variables to be examined will include biological parameters such as S. mutans infection levels, diet, exposure to fluoridated dentifrice and optimally fluoridated water, and frequency of antibiotic usage. Sociodemographic and psychological variables collected will include family income, marital status, parents' oral health status, locus of control, self-efficacy, level of psychosocial stress, and knowledge of dental prevention. After the caries risk factors are identified and the risk assessment model is developed, we will utilize a decision analytic framework and cost-effectiveness analysis to estimate costs and outcomes of various preventive strategies with and without the screening instrument. A precise screening instrument will allow significant improvement in the identification of low income and minority children at high risk for developing dental caries. Dental prevention programs targeted to the caries risk factors in high risk children could then reduce costs greatly.